It was actually one of the "extras" that slipped up. She told Ingrid that she had been "cast" for her role.

Just goes to show that there are no small roles. I blame this one fully on the producers, they didn't bring the extras in early enough and didn't have any back story set up for them. Of course the plan was that they weren't supposed to talk during the lineup but Jane clearly demonstrated that the schmos are an uncontrolled element and they can't plan on them doing specific things.